On Thu, Feb 27, 2025 at 06:08:11PM +0000, John Garry wrote:
> When completing a CoW-based write, each extent range mapping update is
> covered by a separate transaction.
>
> For a CoW-based atomic write, all mappings must be changed at once, so
> change to use a single transaction.
>
> Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
Looks good to me now,
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
--D
> ---
> fs/xfs/xfs_file.c | 5 ++++-
> fs/xfs/xfs_reflink.c | 49 ++++++++++++++++++++++++++++++++++++++++++++
> fs/xfs/xfs_reflink.h | 3 +++
> 3 files changed, 56 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 76ea59c638c3..44e11c433569 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -527,7 +527,10 @@ xfs_dio_write_end_io(
> nofs_flag = memalloc_nofs_save();
>
> if (flags & IOMAP_DIO_COW) {
> - error = xfs_reflink_end_cow(ip, offset, size);
> + if (iocb->ki_flags & IOCB_ATOMIC)
> + error = xfs_reflink_end_atomic_cow(ip, offset, size);
> + else
> + error = xfs_reflink_end_cow(ip, offset, size);
> if (error)
> goto out;
> }
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 97dc38841063..844e2b43357b 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -987,6 +987,55 @@ xfs_reflink_end_cow(
> trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
> return error;
> }
> +int
> +xfs_reflink_end_atomic_cow(
> + struct xfs_inode *ip,
> + xfs_off_t offset,
> + xfs_off_t count)
> +{
> + xfs_fileoff_t offset_fsb;
> + xfs_fileoff_t end_fsb;
> + int error = 0;
> + struct xfs_mount *mp = ip->i_mount;
> + struct xfs_trans *tp;
> + unsigned int resblks;
> +
> + trace_xfs_reflink_end_cow(ip, offset, count);
> +
> + offset_fsb = XFS_B_TO_FSBT(mp, offset);
> + end_fsb = XFS_B_TO_FSB(mp, offset + count);
> +
> + /*
> + * Each remapping operation could cause a btree split, so in the worst
> + * case that's one for each block.
> + */
> + resblks = (end_fsb - offset_fsb) *
> + XFS_NEXTENTADD_SPACE_RES(mp, 1, XFS_DATA_FORK);
> +
> + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
> + XFS_TRANS_RESERVE, &tp);
> + if (error)
> + return error;
> +
> + xfs_ilock(ip, XFS_ILOCK_EXCL);
> + xfs_trans_ijoin(tp, ip, 0);
> +
> + while (end_fsb > offset_fsb && !error) {
> + error = xfs_reflink_end_cow_extent_locked(tp, ip, &offset_fsb,
> + end_fsb);
> + }
> + if (error) {
> + trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
> + goto out_cancel;
> + }
> + error = xfs_trans_commit(tp);
> + xfs_iunlock(ip, XFS_ILOCK_EXCL);
> + return error;
> +out_cancel:
> + xfs_trans_cancel(tp);
> + xfs_iunlock(ip, XFS_ILOCK_EXCL);
> + return error;
> +}
>
> /*
> * Free all CoW staging blocks that are still referenced by the ondisk refcount
> diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
> index dfd94e51e2b4..4cb2ee53cd8d 100644
> --- a/fs/xfs/xfs_reflink.h
> +++ b/fs/xfs/xfs_reflink.h
> @@ -49,6 +49,9 @@ extern int xfs_reflink_cancel_cow_range(struct xfs_inode *ip, xfs_off_t offset,
> xfs_off_t count, bool cancel_real);
> extern int xfs_reflink_end_cow(struct xfs_inode *ip, xfs_off_t offset,
> xfs_off_t count);
> + int
> +xfs_reflink_end_atomic_cow(struct xfs_inode *ip, xfs_off_t offset,
> + xfs_off_t count);
Nit: return type should be at column 0 and the name should be right
after.
int xfs_reflink_end_atomic_cow(struct xfs_inode *ip, xfs_off_t offset,
xfs_off_t count);
With that fixed,
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
--D
> extern int xfs_reflink_recover_cow(struct xfs_mount *mp);
> extern loff_t xfs_reflink_remap_range(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out, loff_t len,
> --
> 2.31.1
>
